Pack-and-a-half architecture for environmental control systems

ABSTRACT

Environmental control systems for aircraft including a ram module having a primary heat exchanger and a secondary heat exchanger, a refrigeration module having an air cycle machine module and a condenser heat exchanger, and a first altitude diverter valve operable from a first position wherein the primary and secondary heat exchangers operate in series and a second position wherein the primary and secondary heat exchanger operate in parallel. Air from the primary and secondary heat exchangers is provided to (i) the condenser heat exchanger when the primary and secondary heat exchangers operate in series and (ii) an aircraft cabin when the primary and secondary heat exchangers operate in parallel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. Provisional Patent Application Nos. 62/309,076, 62/309,080, 62/309,081, and 62/309,084, filed on Mar. 16, 2016. The contents of the priority applications are hereby incorporated by reference in their entireties.

BACKGROUND

The subject matter disclosed herein generally relates to environmental control systems and, more particularly, to pack-and-a-half architectures for environmental control systems.

Commercial aircraft are conventionally equipped with two-pack environmental control system architectures that include redundant packs installed in separate bays beneath a center wing box of the aircraft and are encapsulated by the aircraft wing-to-body fairing. These bays are commonly separated by a Keel Beam that supports the weight of the aircraft in the event of a wheels-up landing. Local penetrations of the keel beam can be accommodated if properly reinforced.

Smaller configurations of environmental control system architectures can include pack-and-a-half architectures that fit within a single volume. However, such volume is larger than half of the convention two-pack architectures, and thus the pack-and-a-half architecture systems may be too large for use in such locations, and thus may be required to be installed in other locations of the aircraft (e.g., in a tail cone of the aircraft). It may be beneficial to further reduce the size of pack-and-a-half environmental control system architectures.

SUMMARY

According to one embodiment, environmental control systems for aircraft are provided. The environmental control systems include a ram module having a primary heat exchanger and a secondary heat exchanger, a refrigeration module having an air cycle machine module and a condenser heat exchanger, and a first altitude diverter valve operable from a first position wherein the primary and secondary heat exchangers operate in series and a second position wherein the primary and secondary heat exchanger operate in parallel. Air from the primary and secondary heat exchangers is provided to (i) the condenser heat exchanger when the primary and secondary heat exchangers operate in series and (ii) an aircraft cabin when the primary and secondary heat exchangers operate in parallel.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include that the primary and secondary heat exchangers operate in series when the aircraft is on the ground.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include that the primary and secondary heat exchangers operate in parallel when the aircraft is in flight.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include a second altitude diverter valve operable to direct air from the primary and secondary heat exchangers to one of the condenser heat exchanger and the aircraft cabin.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include that the air cycle machine module comprises a first air cycle machine and a second air cycle machine, each air cycle machine having a respective compressor and respective turbine.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include a water collector configured downstream from the condenser heat exchanger, the water collector configured to extract water from air supplied from one of the condenser heat exchanger or outflow air from the aircraft cabin.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include that the air cycle machine module is supplied with bleed air, the environmental control system further comprising a quench valve configured to control flow from the primary heat exchanger such that air from the primary heat exchange can be provided to supply cool air to the bleed air and condition said bleed air.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include that the air cycle machine module comprises a first air cycle machine and a second air cycle machine, each air cycle machine having a respective compressor, respective turbine, and respective power turbine.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include that the turbines of the first and second air cycle machines are operated when the aircraft is on the ground and the power turbines of the first and second air cycle machines are operated when the aircraft is in flight.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include a water collector configured downstream from the condenser heat exchanger, the water collector configured to extract water from air supplied from the condenser heat exchanger when the turbines of the first and second air cycle machines are operated and the water collector is bypassed when the power turbines of the first and second air cycle machines are operated.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include at least one overboard diverter valve configured to exhaust air from the air cycle machine module overboard when the aircraft is in flight.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include at least one temperature control valve configured to divert bleed air to the condenser heat exchanger when the aircraft is on the ground.

In addition to one or more of the features described above, or as an alternative, further embodiments of the environmental control systems may include an altitude valve configured to control an airflow from the air cycle machine module to one or both of the heat exchangers of the ram module.

Technical effects of embodiments of the present disclosure include environmental control systems having pack-and-a-half architectures.

The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter is particularly pointed out and distinctly claimed at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1A is a schematic illustration of an aircraft that can incorporate various embodiments of the present disclosure;

FIG. 1B is a schematic illustration of a bay section of the aircraft of FIG. 1A;

FIG. 2A is a schematic, perspective illustration of an environmental control system of an aircraft that can incorporate embodiments of the present disclosure;

FIG. 2B is a second perspective illustration of the environmental control system of FIG. 2A;

FIG. 3 is a schematic diagram of an environmental control system in accordance with an embodiment of the present disclosure;

FIG. 4A is a schematic diagram of an environmental control system architecture in accordance with an embodiment of the present disclosure;

FIG. 4B is a schematic diagram illustrating an airflow through the environmental control system of FIG. 4A when an aircraft is on the ground;

FIG. 4C is a schematic diagram illustrating an airflow through the environmental control system of FIG. 4A when an aircraft is in flight;

FIG. 5A is a schematic diagram of an environmental control system architecture in accordance with another embodiment of the present disclosure;

FIG. 5B is a schematic diagram illustrating an airflow through the environmental control system of FIG. 5A when an aircraft is on the ground; and

FIG. 5C is a schematic diagram illustrating an airflow through the environmental control system of FIG. 5A when an aircraft is in flight.

DETAILED DESCRIPTION

As shown and described herein, various features of the disclosure will be presented. Various embodiments may have the same or similar features and thus the same or similar features may be labeled with the same reference numeral, but preceded by a different first number indicating the figure to which the feature is shown. Thus, for example, element “##” that is shown in FIG. X may be labeled “X##” and a similar feature in FIG. Z may be labeled “Z##.” Although similar reference numbers may be used in a generic sense, various embodiments will be described and various features may include changes, alterations, modifications, etc. as will be appreciated by those of skill in the art, whether explicitly described or otherwise would be appreciated by those of skill in the art.

As shown in FIGS. 1A-1B, an aircraft 101 can include one or more bays 103 beneath a center wing box. The bay 103 can contain and/or support one or more components of the aircraft 101. For example, in some configurations, the aircraft 101 can include environmental control systems within the bay 103. As shown in FIG. 1B, the bay 103 includes bay doors 105 that enable installation and access to one or more components (e.g., environmental control systems). During operation of environmental control systems, air that is external to the aircraft 101 can flow into one or more environmental control systems within the bay doors 105 through one or more ram air inlets 107. The air may then flow through the environmental control systems to be processed and supplied to various components or locations within the aircraft 101 (e.g., passenger cabin, etc.). Some air may be exhaust through one or more ram air exhaust outlets 109.

Turning now to FIGS. 2A-2B, an environmental control system 200 in accordance with an embodiment of the present disclosure is shown. The environmental control system 200 includes a ram module 202 and a refrigeration module 204 that are operably connected by one or more ducts 206 a, 206 b, 206 c. FIG. 2A shows a first perspective illustration of the environmental control system 200 and FIG. 2B shows a second perspective illustration of the environmental control system 200. The environmental control system 200 of FIGS. 2A-2B is merely for illustrative and explanatory purposes, and those of skill in the art will appreciate that various embodiments of the present disclosure can be configured with different types of environmental control systems and/or different configurations of environmental control systems, and thus, the present discussion and associated illustrations are not intended to be limiting.

As shown, in FIGS. 2A-2B, the ram module 202 includes a primary heat exchanger 208 a and a secondary heat exchanger 208 b that form a two-pass heat exchanger module. The heat exchangers 208 a, 208 b are configured to receive ram air A_(ram) and bleed air A_(bleed) to condition air within the ram module 202. The ram module 202 further includes a ram outlet header 210 and a ram exhaust header 212. Located between the headers 210, 212 may be one or more ram fans 214. Air from the ram module 202 can be conveyed to or from the refrigeration module 204 through the ducts 206 a, 206 b, 206 c.

The refrigeration module 204 includes a condenser heat exchanger 216 and one or more air cycle machines 218. The condenser heat exchanger 216 can be operably connected to the secondary heat exchanger 208 b by a first duct 206 a that can supply hot air to the condenser heat exchanger 216. The air cycle machines 218 can be connected to one or both of the heat exchangers 208 a, 208 b, as shown. Recirculated air A_(recirc) can be supplied to and mix with turbine air from the air cycle machines 218 as indicated in FIG. 2A.

The condenser heat exchanger 216 is configured to condition air and supply relatively cool or cold air A_(cabin) to a cabin of an aircraft. Thus, the condenser heat exchanger 216 includes an outlet header 220. The hot air that is supplied to the condenser heat exchanger 216 through the duct 206 a is fed into an inlet header 222 of the condenser heat exchanger 216.

As shown in FIGS. 2A-2B, the ram fans 214 and the air cycle machines 218 are separated. Such a configuration enables the separation of the environmental control system 200 to be separated into the ram module 202 and the refrigeration module 204. As shown, the ram module 202 includes the ram fans 214. In some embodiments, the ram fans 214 can be configured as dual electric ram rams that can provide a required ram cooling performance and redundancy. The ram fans 214 can be operated separately or at the same time to enable control and variance in ram flow. Fixed speed fans, two speed fans, or variable speed fans can be used without departing from the scope of the present disclosure. Accordingly, the environmental control system 200 can be installed into two separate volumes on an aircraft (e.g., in two separate bays) as compared to a single large volume.

For example, turning now to FIG. 3, a schematic diagram of an environmental control system 300 in accordance with an embodiment of the present disclosure is shown. The environmental control system 300 may be similar to that shown and described in FIGS. 2A-2B, and thus like features will not be described again.

The environmental control system 300 includes a ram module 302 and a refrigeration module 304. In some configurations, when installed on an aircraft, the ram module 302 can be installed into a right-hand side of the aircraft, and thus through a first bay door and the refrigeration module 304 can be installed into a left-hand side of the aircraft, and through a second bay door. In FIG. 3, an aircraft centerline 311 is indicated as separating the ram module 302 from the refrigeration module 304.

The ram module 302 is operably connected to the refrigeration module 304 by one or more ducts 306. The environmental control system 300 includes a primary heat exchanger 308 a and a secondary heat exchanger 308 b that receive bleed air A_(bleed) and ram air A_(ram), respectively, to condition air within the ram module 302. One or more ram fans 314 are configured to aid in exhausting ram exhaust air A_(ram) _(_) _(exhaust) from the ram module 302.

As shown, the refrigeration module 304 includes a condenser heat exchanger 316 and tandem air cycle machines 318 a, 318 b. Each of the tandem air cycle machines 318 a, 318 b includes a respective compressor 324 a, 324 b and a respective turbine 326 a, 326 b. The tandem air cycle machines 318 a, 318 b can form a tandem air cycle machine module 328, as indicated by the dashed-line box in FIG. 3. The tandem air cycle machine module 328 can include two air cycle machines (e.g., 318 a, 318 b) that are operably connected to a centralized manifold, as described herein, and thus form a compact, unitized assembly. Although shown and described herein with two air cycle machines 318 a, 318 b, those of skill in the art will appreciate that embodiments of the present disclosure can be applied to two, three, or four wheel tandem air cycle machines. As shown, a water collector 329 is configured to extract moisture from air of the condenser 316 and supply the conditioned air to the air cycle machines 318 a, 318 b. An air cycle machine isolation valve 332 is schematically shown that is configured to be operated and control fluid flow into one or both of the air cycle machines 318 a, 318 b.

Embodiments provided herein are directed to improved pack-and-a-half environmental control systems. Architectures as provided herein can enable an integrated low pressure system that offers improved economic and operational performance superior to other architectures. Moreover, embodiments provided enable reduced system part count, weight, and interfaces that can be realized over conventional two-pack architectures. For example, in various embodiments, architectures provided herein may require only one instead of two of the following components: ram heat exchangers; condensing heat exchangers; water collectors; air cycle machine isolation valves; or ram circuits.

Turning to FIGS. 4A-4C, schematic diagrams of a pack-and-a-half environmental control system 400 in accordance with an embodiment of the present disclosure are shown. FIG. 4A illustrates the components of the environmental control system 400, FIG. 4B illustrates a ground operation of the environmental control system 400, and FIG. 4C illustrates a cruise operation of the environmental control system 400. The dashed lines in FIGS. 4B-4C illustrate flow paths of air as it flows through the environmental control system 400 in the various operational conditions.

The environmental control system 400 can be configured similar to that shown in FIGS. 2A-2B, and includes a first heat exchanger 408 a, a second heat exchanger 408 b, a water collector 429, a condenser heat exchanger 416, and air cycle machines having ram fans 414 a, 414 b, compressors 424 a, 424 b, and turbines 426 a, 426 b. Other features and aspects of the environmental control system 400 are omitted for simplicity. As shown, ram air A_(ram) and bleed air A_(bleed) can enter the environmental control system 400 and ram exhaust air A_(ram) _(_) _(exhaust) and conditioned cabin air A_(cabin) can exit the environmental control system 400. Further, in some embodiments, a portion of the air within the environmental control system 400 can be exhausted overboard as overboard air A_(over), as illustrated in FIGS. 4A-4C.

The environmental control system 400 can include multiple components to control airflow through the environmental control system 400 such that different flow paths of air within the environmental control system 400 can be achieved based on different operating states. For example, as noted above, a ground operation is indicated in FIG. 4B and a cruise operation is indicated in FIG. 4C.

The environmental control system 400 can include multiple valves, sensors, etc. For example, as shown, in addition to an air cycle machine isolation valve 432, the environmental control system 400 includes one or more overboard diverter valves 434 that can be configured downstream from the turbines 426 a, 426 b. One or more temperature control valves 436 can be used to control the turbine outlet temperature using bleed air A_(bleed). The overboard diverter valves 434 are used to either direct flow to the condenser heat exchanger 416 or overboard during cruise operation (A_(over)).

A first altitude diverter valve 438 can be configured to divert air from an outlet HX_(out) of the primary heat exchanger 408 a to an inlet HX_(in) of the secondary heat exchanger 408 b, as shown or allow for air to flow from the outlet HX_(out) of the primary heat exchanger 408 a toward the condenser heat exchanger 416 or to be cabin air A_(cabin). The first altitude diverter valve 438 is configured to enable the heat exchangers 408 a, 408 b to operate in series or in parallel. As second altitude diverter valve 440 can be configured to control air from one or both of the heat exchangers 408 a, 408 b and direct it to the cabin as cabin air A_(cabin) or into the condenser heat exchanger 416. A differential pressure sensor 442 can be configured to monitor a differential air pressure between the cabin air A_(cabin) and air supplied from one or more of the turbines 426 a, 426 b to the condenser heat exchanger 416. The differential pressure sensor 442 can be used, in some embodiments, to aid in control of one or more of the valves of the environmental control system 400 (e.g., the valves described herein or other valves configured within the environmental control system 400).

Additional valves can be configured to control airflow between the heat exchangers 408 a, 408 b and the compressors 424 a, 424 b. For example, a quench valve 444 can be configured to control airflow from an outlet HX_(out) of the primary heat exchanger 408 a to the compressors 424 a, 424 b. Further, an altitude valve 446 can be configured to control an airflow from the compressors 424 a, 424 b to inlets HX_(in) of one or both of the heat exchangers 408 a, 408 b.

As noted, the dashed line in FIG. 4B illustrates a flow path of air through the environmental control system 400 in a ground state of operation. The dashed line in FIG. 4C illustrates a flow path of air through the environmental control system 400 in a cruise state of operation.

As illustrated in FIG. 4B, the first altitude diverter valve 438 is configured to divert air from an outlet HX_(out) of the primary heat exchanger 408 a to an inlet HX_(in) of the secondary heat exchanger 408 b. As such, air from the primary heat exchanger 408 a is not directed toward the condenser heat exchanger 416. However, air from the secondary heat exchanger 408 b is directed through the second altitude diverter valve 440 and supplied to the condenser heat exchanger 416. Further, the altitude valve 446 is configured to prevent air from the compressors 424 a, 424 b to be provided to the secondary heat exchanger 408 b, as shown. The condenser heat exchanger 416 is configured to supply the cabin air A_(cabin) and also provide air to the water collector 429.

Referring now to FIG. 4C, the changes from the ground state of operation (FIG. 4B) to the cruise state of operation of the environmental control system 400 will be discussed. In the cruise state of operation, first altitude diverter valve 438 is oriented to allow airflow from the primary heat exchanger 408 a to flow toward the condenser heat exchanger 416 (rather than being diverted to the secondary heat exchanger 408 b). Further, as shown, the second altitude diverter valve 440 is oriented to bypass the condenser heat exchanger 416 and supply air directly as the cabin air A_(cabin). Because the condenser heat exchanger 416 is bypassed, no air is supplied from the condenser heat exchanger 416 to the water collector 429. However, air can be supplied from a cabin as controlled by an outflow valve 448, through the water collector 429, through the turbines 426 a, 426 b and then exhausted as overboard air A_(over). Further, in the cruise state of operation, the altitude valve 446 can be opened to enable flow from the compressors 424 a, 424 b to the secondary heat exchanger 408 b, as shown.

Turning now to FIGS. 5A-5C, an alternative architecture of an environmental control system in accordance with an embodiment of the present disclosure is shown. FIG. 5A is schematic diagram of a pack-and-a-half architecture of an environmental control system 500. FIG. 5A illustrates the components of the environmental control system 500, FIG. 5B illustrates a ground operation of the environmental control system 500, and FIG. 5C illustrates a cruise operation of the environmental control system 500. The dashed lines in FIGS. 5B-5C illustrate flow paths of air as it flows through the environmental control system 500 in the various operational conditions.

The environmental control system 500 can be configured similar to that shown in FIGS. 2A-2B and/or FIGS. 4A-4C, and includes a first heat exchanger 508 a, a second heat exchanger 508 b, a water collector 529, a condenser heat exchanger 516, and air cycle machines having ram fans 514 a, 514 b, compressors 524 a, 524 b, and turbines 526 a, 526 b. Further, the environmental control system 500 (and particularly the air cycle machines of the environmental control system 500) include power turbines 550 a, 550 b. Other features and aspects of the environmental control system 500 are omitted for simplicity. As shown, ram air A_(ram) and bleed air A_(bleed) can enter the environmental control system 500 and ram exhaust air A_(ram) _(_) _(exhaust) and conditioned cabin air A_(cabin) can exit the environmental control system 500. Further, in some embodiments, a portion of the air within the environmental control system 500 can be exhausted overboard as overboard air A_(over), as illustrated in FIGS. 5A and 5C.

The environmental control system 500 can include multiple components to control airflow through the environmental control system 500 such that different flow paths of air within the environmental control system 500 can be achieved based on different operating states. For example, as noted above, a ground operation is indicated in FIG. 5B and a cruise operation is indicated in FIG. 5C.

The environmental control system 500 can include multiple valves, sensors, etc. As shown in FIG. 5A, the air cycle machine isolation valve 532 is configured to control air flow to the turbines 526 a, 526 b or the power turbines 550 a, 550 b. During operation, the turbines 526 a, 526 b can be supplied with air from the water collected 529, or the power turbines 550 a, 550 b can be supplied with air from a cabin as controlled an outflow valve 548, depending on the state of the air cycle machine isolation valve 532. One or more temperature control valves 536 can be used to divert bleed air A_(bleed) to the condenser heat exchanger 516.

A first altitude diverter valve 538 can be configured to divert air from an outlet HX_(out) of the primary heat exchanger 508 a to an inlet HX_(in) of the secondary heat exchanger 508 b, as shown or allow for air to flow from the outlet HX_(out) of the primary heat exchanger 508 a toward the condenser heat exchanger 516 or to be cabin air A_(cabin). The first altitude diverter valve 538 is configured to enable the heat exchangers 508 a, 508 b to operate in series or in parallel. As second altitude diverter valve 540 can be configured to control air from one or both of the heat exchangers 508 a, 508 b and direct it to the cabin as cabin air A_(cabin) or into the condenser heat exchanger 516. A differential pressure sensor 542 can be configured to monitor a differential air pressure between the cabin air A_(cabin) and air supplied from one or more of the turbines 526 a, 526 b to the condenser heat exchanger 516. The differential pressure sensor 542 can be used, in some embodiments, to aid in control of one or more of the valves of the environmental control system 500 (e.g., the valves described herein or other valves configured within the environmental control system 500).

Additional valves can be configured to control airflow between the heat exchangers 508 a, 508 b and the compressors 524 a, 524 b. For example, a quench valve 544 can be configured to control airflow from an outlet HX_(out) of the primary heat exchanger 508 a to the compressors 524 a, 524 b. Further, an altitude valve 546 can be configured to control an airflow from the compressors 524 a, 524 b to inlets HX_(in) of one or both of the heat exchangers 508 a, 508 b.

As noted, the dashed lines in FIG. 5B illustrate a flow path of air through the environmental control system 500 in a ground state of operation. The dashed lines in FIG. 5C illustrates a flow path of air through the environmental control system 500 in a cruise state of operation.

As illustrated in FIG. 5B, the first altitude diverter valve 538 is configured to divert air from an outlet HX_(out) of the primary heat exchanger 508 a to an inlet HX_(in) of the secondary heat exchanger 508 b. As such, air from the primary heat exchanger 508 a is not directed toward the condenser heat exchanger 516. However, air from the secondary heat exchanger 508 b is directed through the second altitude diverter valve 540 and supplied to the condenser heat exchanger 516. Further, the altitude valve 546 is configured to prevent air from the compressors 524 a, 524 b to be provided to the secondary heat exchanger 508 b, as shown. The condenser heat exchanger 516 is configured to supply the cabin air A_(cabin) and also provide air to the water collector 529.

Referring now to FIG. 5C, the changes from the ground state of operation (FIG. 5B) to the cruise state of operation of the environmental control system 500 will be discussed. In the cruise state of operation, first altitude diverter valve 538 is oriented to allow airflow from the primary heat exchanger 508 a to flow toward the condenser heat exchanger 516 (rather than being diverted to the secondary heat exchanger 508 b). Further, as shown, the second altitude diverter valve 540 is oriented to bypass the condenser heat exchanger 516 and supply air directly as the cabin air A_(cabin). Because the condenser heat exchanger 516 is bypassed, no air is supplied from the condenser heat exchanger 516 to the water collector 529. However, air can be supplied from the outflow valve 548 and bypass the water collector 529 by operation of the air cycle machine isolation valve 532. The air can also be diverted away from the turbines 526 a, 526 b and instead conveyed to the power turbines 550 a, 550 b and subsequently diverted to the ram out as ram exhaust air A_(ram) _(_) _(exhaust). Further, in the cruise state of operation, the altitude valve 546 can be opened to enable flow from the compressors 524 a, 524 b to the secondary heat exchanger 508 b, as shown.

Advantageously, embodiments described herein provide improved pack-and-a-half environmental control systems. For example, advantageously, embodiments provided herein enable redundancy where needed for dispatch reliability (e.g., air cycle machine and temperature control valve). Further, advantageously, the use of a two-pass ram heat exchanger operating in series on the ground (e.g., FIGS. 4A, 5A) and in parallel in flight (e.g., FIGS. 4B, 5B) by operation of an altitude diverter valve can enable low pack impedance. Such parallel or series operation of the dual heat exchanger arrangement can enable lower bleed pressure during flight (e.g., cruise) that can result in a fuel savings benefit.

Further, advantageously, in some embodiments, the air cycle machines can utilize mixed-flow compressors (e.g., bleed air, heat exchanger air, etc.) offering a wide range of performance over a system operating profile. Such performance range can enable relatively low supply pressures from an aircraft engine to be efficiently boosted in-flight to pressurize the cabin.

In various embodiments, the turbines of the air cycle machines can be used as a cooling turbine for ground operation and a power turbine (driven by outflow air from a cabin) in flight. A common turbine (e.g., FIG. 4A) or separate turbines (e.g., FIG. 5A) may be used.

In various embodiments, a quench valve can be provided to supply cool air to a compressor inlet when bleed inlet air temperatures need to be tempered to a level to permit the use of lightweight materials (e.g., aluminum) in the system.

The various altitude valves and altitude diverter valves are used reconfigure the pack-and-a-half system architecture for low impedance (e.g., a fuel saving mode). Further, in some embodiments, an outflow valve can control an airflow from a cabin to the turbines (e.g., common turbines, FIG. 4A) or the power turbines (e.g., separate turbines, FIG. 5A). The temperature control valves of various embodiments can be configured to regulate turbine outlet temperatures.

The use of the terms “a,” “an,” “the,” and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. It should be appreciated that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to normal operational attitude and should not be considered otherwise limiting.

While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions, combinations, sub-combinations, or equivalent arrangements not heretofore described, but which are commensurate with the scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments.

Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims. 

What is claimed is:
 1. An environmental control system for an aircraft, the environmental control system comprising: a ram module having a primary heat exchanger and a secondary heat exchanger; a refrigeration module having an air cycle machine module and a condenser heat exchanger; and a first altitude diverter valve operable from a first position wherein the primary and secondary heat exchangers operate in series and a second position wherein the primary and secondary heat exchanger operate in parallel, wherein air from the primary and secondary heat exchangers is provided to (i) the condenser heat exchanger when the primary and secondary heat exchangers operate in series and (ii) an aircraft cabin when the primary and secondary heat exchangers operate in parallel.
 2. The environmental control system of claim 1, wherein the primary and secondary heat exchangers operate in series when the aircraft is on the ground.
 3. The environmental control system of claim 1, wherein the primary and secondary heat exchangers operate in parallel when the aircraft is in flight.
 4. The environmental control system of claim 1, further comprising a second altitude diverter valve operable to direct air from the primary and secondary heat exchangers to one of the condenser heat exchanger and the aircraft cabin.
 5. The environmental control system of claim 1, wherein the air cycle machine module comprises a first air cycle machine and a second air cycle machine, each air cycle machine having a respective compressor and respective turbine.
 6. The environmental control system of claim 1, further comprising a water collector configured downstream from the condenser heat exchanger, the water collector configured to extract water from air supplied from one of the condenser heat exchanger or outflow air from the aircraft cabin.
 7. The environmental control system of claim 1, wherein the air cycle machine module is supplied with bleed air, the environmental control system further comprising a quench valve configured to control flow from the primary heat exchanger such that air from the primary heat exchange can be provided to supply cool air to the bleed air and condition said bleed air.
 8. The environmental control system of claim 1, wherein the air cycle machine module comprises a first air cycle machine and a second air cycle machine, each air cycle machine having a respective compressor, respective turbine, and respective power turbine.
 9. The environmental control system of claim 8, wherein the turbines of the first and second air cycle machines are operated when the aircraft is on the ground and the power turbines of the first and second air cycle machines are operated when the aircraft is in flight.
 10. The environmental control system of claim 8, further comprising a water collector configured downstream from the condenser heat exchanger, the water collector configured to extract water from air supplied from the condenser heat exchanger when the turbines of the first and second air cycle machines are operated and the water collector is bypassed when the power turbines of the first and second air cycle machines are operated.
 11. The environmental control system of claim 1, further comprising at least one overboard diverter valve configured to exhaust air from the air cycle machine module overboard when the aircraft is in flight.
 12. The environmental control system of claim 1, further comprising at least one temperature control valve configured to divert bleed air to the condenser heat exchanger when the aircraft is on the ground.
 13. The environmental control system of claim 1, further comprising an altitude valve configured to control an airflow from the air cycle machine module to one or both of the heat exchangers of the ram module. 